WebSocket: open event - Web APIs | MDN
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WebSocket: open event
Baseline
Widely available
This feature is well established and works across many devices and browser versions. It’s been available across browsers since July 2015.
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Note:
This feature is available in
Web Workers
The
open
event is fired when a connection with a
WebSocket
is opened.
Syntax
Use the event name in methods like
addEventListener()
, or set an event handler property.
js
addEventListener("open", (event) => { })
onopen = (event) => { }
Event type
A generic
Event
Examples
js
// Create WebSocket connection.
const socket = new WebSocket("ws://localhost:8080");
// Connection opened
socket.addEventListener("open", (event) => {
socket.send("Hello Server!");
});
Specifications
Specification
WebSockets
# dom-websocket-onopen
Browser compatibility
See also
WebSocket: close event
WebSocket: error event
WebSocket: message event
Writing WebSocket client applications
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This page was last modified on
May 2, 2025
by
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